Long range B-site cation ordering and Briet–Wigner–Fano line shape of A{sub 1g}-like Raman mode in Nd{sub 1−x}Sm{sub x}(Mg{sub 0.5}Ti{sub 0.5})O{sub 3} microwave dielectric ceramics

Journal Article · Fri Feb 15 04:00:00 EST 2013 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2012.09.056· OSTI ID:22215787

Kiran, S. Roopas ^[1]; Babu, G. Santosh; Narayana, Chandrabhas ^[2]; Murthy, V. R.K., ^[1]; Subramanian, V. ^[1]

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1. Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)
2. Light Scattering Laboratory, Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

Graphical abstract: Display Omitted Highlights: ► Q × f of Nd{sub 1–x}Sm{sub x}(Mg{sub 0.5}Ti{sub 0.5})O{sub 3} are correlated with B-site cation ordering (LRO). ► Correlation between LRO and Γ of A{sub 1g}-like mode in Raman spectrum is observed. ► Reason for asymmetry in A{sub 1g}-like Raman mode in these materials is revealed. ► Briet–Wigner–Fano resonance is confirmed with temperature variation in Raman spectra. -- Abstract: Nd{sub 1−x}Sm{sub x}(Mg{sub 0.5}Ti{sub 0.5})O{sub 3} (x = 0.0–1.0) samples were prepared by solid-state reaction method. Rietveld refinement of X-ray diffraction data was done using P2{sub 1}/n space group with monoclinic symmetry, which supports 1:1 B-site cation ordering. Long range ordering (LRO) parameter decreased up to x = 0.5 and then found to increase with further increase in Sm concentration. The A{sub 1g}-like mode in Raman spectra was observed to possess Briet–Wigner–Fano line shape. The variation in obtained line width of the A{sub 1g}-like mode supported LRO. Microwave dielectric characteristics such as dielectric constant (ε{sub r}), quality factor (Q) and temperature coefficient of resonant frequency (τ{sub f}) were measured in the range of 7–9 GHz. ε{sub r} decreased from 26.5 to 24.9 and τ{sub f} become less negative from −58 ppm/°C to −36 ppm/°C with increase in Sm concentration. Q × f decreased from 47,500 GHz (for x = 0) to 39,800 GHz (for x = 0.5) and then increased to 44,600 GHz (for x = 1).

• OSTI ID: 22215787
• Journal Information: Materials Research Bulletin, Journal Name: Materials Research Bulletin Journal Issue: 2 Vol. 48; ISSN MRBUAC; ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CATIONS
DIELECTRIC MATERIALS
MONOCLINIC LATTICES
PERMITTIVITY
QUALITY FACTOR
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SPACE GROUPS
TEMPERATURE COEFFICIENT
X-RAY DIFFRACTION